Battery with front face and rear face contacts

ABSTRACT

A battery structure has structure anode and cathode contacts on a front face and on a rear face. The battery structure includes a battery having battery anode and cathode contacts only on a front face thereof. A film including a conductive layer and an insulating layer jackets the battery. The conductive layer extends over the battery anode and cathode contacts and is interrupted therebetween. Openings are provided in the insulating layer on the front and rear faces of the battery structure to form the structure anode and cathode contacts of the battery structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of United States Application for patentSer. No. 15/699,233 filed Sep. 8, 2017, which claims the prioritybenefit of French Application for Patent No. 1750771, filed on Jan. 31,2017, the disclosures of which are hereby incorporated by reference intheir entireties to the maximum extent allowable by law.

TECHNICAL FIELD

The present application relates to a battery with contacts on the frontface and on the rear face and a method for modifying a battery havinganode and cathode contacts on the front face into a battery having anodeand cathode contacts on the front face and on the rear face.

BACKGROUND

FIGS. 1A and 1B illustrate a planar electronic component 1 of squareform. The electronic component 1 can, for example, be a microbattery ora lithium battery.

FIG. 1A is a plan view. The component 1 comprises two contactmetallizations 3 and 5 respectively, for example, the cathode (+) andanode (−) terminals of a battery. The metallizations 3 and 5 arepositioned on an edge of the component 1, for example on two consecutive(i.e., adjacent) corners of a top face 7 of the component 1. Eachcontact metallization 3, 5 is for example of triangular form and has avertex corresponding to a corner of the component 1.

FIG. 1B is a side view of the electronic component 1. The contactmetallization 5 is positioned in a corner of the top face 7 of thecomponent 1 but does not extend right through to the bottom face. Thesame applies for the contact metallization 3, not visible in FIG. 1B.

FIG. 2 illustrates an example of parallel assembly of electroniccomponents 1 of the type of that presented in FIGS. 1A and 1B. Thecomponents are stacked according to an axis Z orthogonal to the plane ofthe components and of the figure, and are staggered relative to oneanother by a length L, along an axis X orthogonal to the axis Z and tothe side of the component bearing the metallizations 3 and 5. The lengthL is chosen to reveal the contact metallizations 3 and 5 of eachsuccessive component 1. To produce a parallel assembly, the contactmetallizations 3 and 5 of the components 1 are respectivelyinterconnected by connections 11 and 13, for example lines of solder.

The assembly of FIG. 2 presents the drawback of being bulky andunreliable when it involves stacking a large number of components.

SUMMARY

One embodiment provides for making the anode and cathode contacts of abattery accessible on both faces of said battery.

Thus, one embodiment provides a battery structure having anode andcathode contacts on the front face and on the rear face comprising abattery having anode and cathode contacts on the front face only, thisbattery being jacketed in a film comprising a conductive layer and aninsulating layer, the conductive layer resting on the anode and cathodecontacts of the battery and being interrupted between these anode andcathode contacts, and the insulating layer comprising openings on thefront and rear faces of the battery to form anode and cathode contactsof the battery structure.

According to one embodiment, the film is fixed to the battery by anadhesive layer.

According to one embodiment, a first cavity and a second cavity passthrough the conductive layer and the adhesive layer, the first cavitybeing positioned above the anode contact and the second cavity beingpositioned above the cathode contact, said cavities being filled with aconductive material.

Another embodiment provides a method for modifying a battery havinganode and cathode contacts on the front face, comprising: covering ofthe front face of the battery with a film comprising an insulating layerand a conductive layer, this film being folded down over the rear faceof the battery, production of a trench in the conductive layer tointerrupt the latter between the front face anode and cathode contactsof the battery, production of openings in the insulating layer so as toreveal contacts on the front face and on the rear face of the finalbattery.

According to one embodiment, the trench is produced before the coveringof the battery with the film.

According to one embodiment, the openings are produced before thecovering of the battery with the film.

According to one embodiment, the film is fixed onto the battery by anadhesive layer.

According to one embodiment, a first cavity is produced in the adhesivelayer and the conductive layer then filled with a conductive material toconnect the conductive layer and the anode contact, and a second cavityis produced in the adhesive layer and the conductive layer then filledwith conductive material to connect the conductive layer and the cathodecontact.

According to one embodiment, the insulating layer is glued to theconductive layer.

According to one embodiment, the insulating layer has a thickness ofbetween 10 and 30 μm.

According to one embodiment, the insulating layer is made ofpolyethylene terephthalate.

According to one embodiment, the conductive layer has a thickness ofbetween 10 and 30 μm.

According to one embodiment, the conductive layer is made of a metal.

According to one embodiment, the conductive layer is made of aluminum.

BRIEF DESCRIPTION OF THE DRAWINGS

These features and advantages, and others, will be explained in detailin the following description of particular embodiments given in anon-limiting manner in relation to the attached figures in which:

FIGS. 1A and 1B, described previously, are plan and side views of abattery;

FIG. 2, described previously, is a plan view of a stacking of batteriesof FIGS. 1A and 1B;

FIG. 3 is a perspective view of an embodiment of a battery;

FIGS. 4A and 4B are perspective views of stackings of batteries of thetype of that of FIG. 3;

FIG. 5 is a detailed cross-sectional view of an embodiment of a batteryat an intermediate step of a method for modifying a battery of the typeof that of FIGS. 1A and 1B;

FIG. 6 is a plan view of a film used in the battery of FIG. 5;

FIG. 7 is a detailed cross-sectional view of the battery of FIG. 5 at afinal step of its manufacturing method; and

FIG. 8 is a plan view of a variant embodiment of the film of FIG. 6.

DETAILED DESCRIPTION

Same elements have been designated by the same references in thedifferent figures and, in addition, the various figures are not drawn toscale. In the interests of clarity, only the elements that are useful tounderstanding the embodiments described have been represented and aredetailed.

In the following description, when reference is made to absoluteposition qualifiers, such as the terms “front”, “rear”, “left”, “right”,etc., or relative position qualifiers, such as the terms “above”,“below”, “top”, “bottom”, etc., reference is made to the orientation ofthe figures in a normal position of use. Unless specified otherwise, theexpression “of the order of” means to within 10%, preferably to within5%.

FIG. 3 is a perspective view of an embodiment of a battery 20. Thebattery 20 comprises, on its front face 22, an anode contact (−) 24 anda cathode contact (+) 26. The battery 20 also comprises, on its rearface 28, an anode contact (−) 30 and a cathode contact (+) 32. As anexample, the anode contact 24 is placed facing the anode contact 30 andthe cathode contact 26 is placed facing the cathode contact 32. A block34 designates the rest of the battery, that is to say the active layersof the battery, such as the anode, cathode and electrolyte layers, andpossibly the substrate on which the battery is formed. The battery 20 isfor example a lithium battery, and can be a lithium microbattery formedby the deposition of thin layers on a thin substrate. An advantage ofbatteries with anode and cathode contacts on the front face and on therear face is that it is possible to stack them vertically as will beshown in relation to FIGS. 4A and 4B.

As an example, as is represented in FIG. 3, the battery has a square orrectangular form, but, as a variant, the battery 20 could have any otherform, for example circular. As an example, as is represented in FIG. 3,the anode and cathode contacts are of square form and are disposed incorners of the battery 20, but, as a variant, these contacts will beable to be triangular, polygonal or circular and be disposed in variousways on the battery 20, for example on protruding areas.

As a variant, the anode and cathode contacts of the battery 20 will beable to be flush with the surfaces 22 and 28 of the battery, even beslightly set back relative to these surfaces 22 and 28.

FIGS. 4A and 4B are perspective views of various possible assemblies ofbatteries 20.

FIG. 4A represents a parallel assembly of three batteries 20A, 20B and20C of FIG. 3. The batteries 20A, 20B and 20C are stacked so as to:

position the rear face anode contact of each upper battery on the frontface anode contact of the immediately lower battery; and

position the rear face cathode contact of each upper battery on thefront face cathode contact of the immediately lower battery.

The cathode contact of the battery obtained by the assembly is formed bythe cathode contacts of the batteries 20A, 20B and 20C. The anodecontact of the battery obtained by the assembly is formed by the anodecontacts of the batteries 20A, 20B and 20C. In practice, the contactconnections will be able to be made on the anode and cathode contacts ofthe upper battery 20A of the assembly or on the anode and cathodecontacts of the lower battery 20C of the assembly.

FIG. 4B represents a series assembly of three batteries 20D, 20E and 20Fof FIG. 3. In this case, the batteries 20D, 20E and 20F are stackedvertically, and each battery undergoes a rotation of 90 degrees relativeto the preceding one, in order to place the front face anode contact ofthe upper battery facing the front face cathode contact of theimmediately lower battery.

The cathode contact of the battery obtained by the assembly is formed bythe cathode contact 26D of the top battery 20D of the assembly. Theanode contact of the battery obtained by the assembly is formed by theanode contact 30F of the bottom battery 20F of the assembly.

The batteries are fixed to one another for example with a conductiveglue disposed at the level of the contacts to be linked. In the case ofbatteries comprising anode and cathode contacts slightly set back, thequantity of conductive glue will be adjusted in order to ensure a goodelectrical connection between two facing contacts to be connected. Theassembly can be embedded in an encapsulation material.

Furthermore, in order to obtain mechanically robust assemblies, in thecase of batteries comprising protruding anode and cathode contacts, itis possible to use spacers (not represented in FIGS. 4A and 4B) to bedisposed between the batteries. In the case of contacts that are flushor slightly set back, the batteries can simply be fixed two by two by anadhesive material.

FIG. 5 is a cross-sectional view of an intermediate step of anembodiment of a method for modifying an initial battery with contacts onthe front face of the type of that described in relation to FIGS. 1A and1B into a final battery with contacts on the front face and on the rearface of the type of that described in relation to FIG. 3.

The initial battery comprises a block 50, an anode contact 52 and acathode contact 54. The block 50 designates all the active layers of theinitial battery and for example the substrate on which it is produced.The anode contact 52 is disposed on the top face of the block 50, on theright of FIG. 5. The cathode contact 54 is disposed on the top face ofthe block 50, on the left of FIG. 5.

A film 60 is disposed on the front face of the initial battery thenfolded down over its sides and its rear face to form the final battery.The film 60 is, for example, fixed onto the battery using an adhesivelayer 62. The adhesive layer 62 is, for example, a polymer (acrylic,solvent or thermofusible glue). The adhesive layer 62 can have athickness of between 10 and 30 μm, for example of the order of 25 μm.The film 60 comprises a conductive layer 64 in contact with the adhesivelayer 62. The conductive layer 64 is, for example, made of a metal, forexample, aluminum. The conductive layer 64 can have a thickness ofbetween 10 and 30 μm, for example of the order of 25 μm. The conductivelayer 64 is glued to an insulating layer 66 via a layer of glue 68. Theinsulating layer 66 is, for example, made of a polymer commonly calledPET (polyethylene terephthalate). The insulating layer 66 can have athickness of between 10 and 30 μm, for example of the order of 23 μm.The layer of glue 68 is, for example, made of a polymer (acrylic orsolvent or thermofusible glue). The layer of glue 68 can have athickness of between 1 and 10 μm, for example of the order of 2 μm.

A trench 70 is produced in the conductive layer 64 of the film 60 inorder to interrupt this conductive layer between the anode contact andthe cathode contact, such that the anode 52 and cathode 54 contacts arenot electrically connected by the conductive layer 64. The trench 70 isfor example produced by laser etching, for example using an ytterbiumlaser. The trench 70 has a width of between 20 μm and 2 mm, for exampleof the order of 1 mm.

Openings 72A and 72B are produced in the layers 62 and 64 of the film 60facing the anode and cathode contacts of the initial battery. Theopening 72A uncovers a portion 54A of the cathode contact 54. Theopening 72B uncovers a portion 52B of the anode contact 52. The openings72A and 72B are, for example, produced by laser etching, for exampleusing an ytterbium laser. The openings 72A and 72B have a width ofbetween 50 μm and 5 mm, for example of the order of 1 mm.

Openings 74A and 74B are produced in the insulating layer 66 and thelayer of glue 68 of the film 60, for example, facing the anode andcathode contacts 52 and 54 of the initial battery. The openings 72A and72B are, for example, produced in the respective continuities of theopenings 74A and 74B and have a width less than that of the openings 74Aand 74B. The opening 74A uncovers a portion 64A of the conductive layer64. The opening 74B thus uncovers a portion 64B of the conductive layer64. The openings 74A and 74B are, for example, produced by laseretching, for example using a carbon dioxide laser. The openings 74A and74B have, for example, a width of between 100 μm and 20 mm, for exampleof the order of 5 mm.

Openings 76A and 76B are produced in the layers 66 and 68 of the film 60on the side of the rear face of the final battery. The openings 76A and76B are, for example, produced facing the openings 74A and 74B. Theopening 76A uncovers a portion 64C of the conductive layer 64. Theopening 76B uncovers a portion 64D of the conductive layer 64. Theopenings 76A and 76B are, for example, produced by laser etching, forexample using a CO₂ laser. The openings 76A and 76B have, for example, awidth of between 100 μm and 20 mm, for example of the order of 5 mm.

As an example, before it is mounted over the battery, the film ispositioned with conductive face 64 at the front. The trench 70 is etchedin the conductive layer 64. The film is then positioned with theinsulating face at the front. The openings 74A, 74B, 76A and 76B areetched in the insulating layer and in the layer of glue. Then, theadhesive layer 62 is fixed onto the free face of the conductive layer 64of the film 60. The openings 72A and 72B are etched in the conductivelayer 64 and in the adhesive layer 62. The film is for example thendeposited on the initial battery, for example by lamination.

FIG. 6 is a plan view of an exemplary embodiment of a film 60 describedin relation to FIG. 5 before it is put in place on the initial battery.The film 60 is, for example, of rectangular form and has dimensionsmatched to the dimensions of the battery to be covered. The film 60 isfolded down over the battery according to folds 78 symbolized by dottedlines.

The openings 72A and 72B are, for example, of circular form and passright through a thickness of the film 60. The openings 74A and 74B are,for example, of triangular form. The openings 76A and 76B are, forexample, of triangular form. An example of the path of the trench 70 issymbolized by dotted lines.

FIG. 7 is a cross-sectional view of a subsequent step to that describedin relation to FIG. 5. In this step, the anode and cathode contacts ofthe final battery are formed. For that, the openings 72A and 72B arefilled with a conductive material 80, for example a metal (silver) epoxyglue, or flowable solder microballs (BUMP) or even conductive (inkjet).Thus, the anode and cathode contacts 52 and 54 of the initial batteryare linked electrically to the conductive layer 64. The trench 70prevents the short-circuiting of the anode and the cathode of theinitial battery. Next, conductive BUMP contacts 82A are formed in theopenings 74A and 76A. The conductive BUMP contacts 82A constitute thecathode contacts of the final battery. Conductive BUMP contacts 82B areformed in the openings 74B and 76B. The conductive BUMP contacts 82Bconstitute the anode contacts of the final battery.

As a variant, the formation of the BUMP contacts 82A and 82B can beomitted. The portions 64A, 64B, 64C and 64D of the conductive layer 64then form anode and cathode contacts on the two faces of the battery.

As a variant, certain portions 64A, 64B, 64C and 64D of the conductivelayer 64 will be able to be provided with conductive BUMP contacts whileothers will not. For example, the anode and cathode contacts of one andthe same face of the battery will be able to be provided with conductiveBUMP contacts whereas the anode and cathode contacts of the oppositeface will not. Thus, the conductive BUMP contacts of one face of thebattery will be able to be adapted to be connected to the contactswithout conductive BUMP contacts of the opposite face of a secondbattery.

FIG. 8 is a plan view of a variant embodiment of a film 60. An advantageof the use of a film such as the film 60 is that it is possible toproduce anode and cathode contacts of various sizes and of variousforms. Thus, the film 60 comprises openings 74A, 74B, 76A and 76B ofrectangular form revealing portions 64A, 64B, 64C and 64D of theconductive layer 64 of greater surface area than those of the film 60presented in relation to FIG. 6. Similarly, it would also be possible toreduce the surface area of the portions 64A, 64B, 64C and 64D.

Particular embodiments have been described. Miscellaneous variants andmodifications will become apparent to a person skilled in the art. Inparticular, it is possible to produce the trench 70 and the openings72A, 72B, 74A, 74B, 76A and 76B once the film 60 is deposited on thebattery.

It is obvious to a person skilled in the art that it is possible tomount contacts on the lateral faces of a battery and not only on itsrear face.

The film could be in the form of a cross and could thus cover the fourlateral faces of a battery in straight block form. Similarly, the filmcould be adapted to different forms of batteries.

It is obvious to a person skilled in the art that it would be possibleto produce contacts on the front face of the battery without thesecontacts being positioned directly in line with the contacts of theinitial battery.

The modification method described here will be able to be applied toelectronic components other than a battery, for example electronicchips, integrated circuits, etc. More particularly, this modificationmethod will be able to be applied to components having more than twoterminals to be mounted on other faces of said components.

Miscellaneous embodiments with miscellaneous variants have beendescribed above. It will be noted that a person skilled in the art willbe able to combine miscellaneous elements of these miscellaneousembodiments and variants without demonstrating inventive step.

1. A method, comprising: covering of a front face of the battery with afilm comprising an insulating layer and a conductive layer, whereinanode and cathode contacts of the battery are located on only the frontface of the battery; folding the film down over a rear face of thebattery; producing a trench in the conductive layer to interrupt theconductive layer between the battery anode and cathode contacts on thefront face of the battery such that the battery anode and cathodecontacts are not electrically connected by the conductive layer; andproducing openings in the insulating layer so as to form: package anodeand cathode contacts on a front face of a battery structure above thebattery anode and cathode contacts; and package anode and cathodecontacts on a rear face of the battery structure.
 2. The methodaccording to claim 1, wherein producing the trench is performed beforecovering of the front face and folding the film.
 3. The method accordingto claim 1, wherein producing openings is performed before the coveringof the front face and folding the film.
 4. The method according to claim1, further comprising adhesively attaching the film onto the batteryusing an adhesive layer.
 5. The method according to claim 4, whereinproducing openings in the insulating layer so as to form package anodeand cathode contacts on the front face of the battery structurecomprises producing a first cavity in the adhesive layer and producing asecond cavity in the adhesive layer.
 6. The method according to claim 5,further comprising filling the first and second cavities with aconductive material to connect the conductive layer to each of thebattery anode contact and battery cathode contact.
 7. The methodaccording to claim 1, wherein the insulating layer is glued to theconductive layer.
 8. The method according to claim 1, wherein theinsulating layer has a thickness of between 10 and 30 μm.
 9. The methodaccording to claim 1, wherein the insulating layer is made ofpolyethylene terephthalate.
 10. The method according to claim 1, whereinthe conductive layer has a thickness of between 10 and 30 μm.
 11. Themethod according to claim 1, wherein the conductive layer is made of ametal.
 12. The method according to claim 11, wherein the metal for theconductive layer is aluminum.
 13. A method, comprising: attaching a filmcomprising an insulating layer and a conductive layer to a battery withthe conductive layer in electrical contact with anode and cathodecontacts of the battery present on only the front face of the battery,wherein said film covers at least part of a front face of the battery,at least part of a side edge of the battery and at least part of a rearface of the battery; opening a trench in the conductive layer of thefilm, said trench extending to interrupt the conductive layer andelectrically disconnect the battery anode contact from the batterycathode contacts; and producing openings in the insulating layer toexpose the conductive layer and form: package anode and cathode contactsassociated with the front face above the battery anode and cathodecontacts; and package anode and cathode contacts associated with therear face.
 14. The method according to claim 13, wherein opening thetrench is performed before covering of the front face and folding thefilm.
 15. The method according to claim 13, wherein producing openingsis performed before the attaching the film.
 16. The method according toclaim 16, wherein attaching the film comprises adhesively attaching thefilm using an adhesive layer.
 17. The method according to claim 16,wherein producing openings comprises producing a first cavity in theadhesive layer and producing a second cavity in the adhesive layer. 18.The method according to claim 17, further comprising filling the firstand second cavities with a conductive material to connect the conductivelayer to each of the battery anode contact and battery cathode contact.19. The method according to claim 13, wherein the insulating layer ismade of polyethylene terephthalate.
 20. The method according to claim13, wherein the conductive layer is made of a metal.
 21. The methodaccording to claim 20, wherein the metal for the conductive layer isaluminum.